ABSTRACT
In this chapter, the authors discuss the flow of water and air through unsaturated coarse-grained soil by means of the elementary particulate model (EPM) for the pore structure. The water flow through the narrow tube is regarded as the laminar flow and Poiseuille’s law is applied to derive the coefficient of water permeability. The coefficient of water permeability obtained by Equation is implicitly considered to be the coefficient for the vertical direction. It is well known that the coefficient of water permeability is generally anisotropic. The anisotropy of water permeability can be estimated by shifting the distribution of predominant flow direction defined by Equation in the EPM. The pore size distribution for the permeability estimated by using the void ratio is considered to be the first approximate distribution for the permeability.
